* feat: add expand_light_groups option
Some light group entities act as a proxy that must receive a single combined
`light.turn_on` call to function correctly — virtual mixers like
<https://github.com/mion00/color-temperature-light-mixer> for instance,
that blend a warm and a cold white channel into one entity. In such setups the
individual member entities only expose `ColorMode.BRIGHTNESS`, so sending
separate per-member commands bypasses the mixing logic.
Setting `expand_light_groups: false` keeps the group entity in `self.lights`
instead of expanding it to its members. Adaptation commands go to the group,
and the interceptor no longer skips group entities for that switch.
Default is `true` — no behaviour change for existing configurations.
* tests: regression test for expand_light_groups=False
_switches_with_lights was expanding the incoming entity_id globally,
causing the switch to never be found when expand_light_groups=False
* Resolve group targets consistently across adaptation paths
* Discard delayed group events after target changes
* Stabilize delayed group target regression test
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Co-authored-by: Bas Nijholt <bas@nijho.lt>
aa84eda871